Prior art blowout preventer shear rams include a type in which a seal is provided for the face or faces of the shear blades to seal against (U.S. Pat. No. 3,651,526 to L. E. Williams, Jr. et al) and another type in which the seal for the blades is contained in a recess in one of the blades to seal against the other shear blade along the shear plane (U.S. Pat. No. 3,817,326 to M. J. Meynier III and U.S. Pat. No. 3,736,982 to A. N. Vujasinavic). For each time these rams are operated to shear, they are operated a great number of times to act as blind rams. The service life of such shear rams is limited by excessive ram packing forces which result from limited packing area and the excessively wide crack between confronting blade surfaces which is bridged by packing. Also with the prior art pipe shear rams for blowout preventers little attention is given to assure that the pieces of the sheared pipe do not interfere with the sealing.